REALPATH(3P)                                        POSIX Programmer's Manual                                       REALPATH(3P)



PROLOG
       This  manual  page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (con-
       sult the corresponding Linux manual page for details of Linux behavior), or the  interface  may  not  be  implemented  on
       Linux.

NAME
       realpath - resolve a pathname

SYNOPSIS
       #include <stdlib.h>

       char *realpath(const char *restrict file_name,
              char *restrict resolved_name);


DESCRIPTION
       The realpath() function shall derive, from the pathname pointed to by file_name, an absolute pathname that names the same
       file, whose resolution does not involve '.', '..', or symbolic links. The generated pathname shall be stored as  a  null-
       terminated string, up to a maximum of {PATH_MAX} bytes, in the buffer pointed to by resolved_name.

       If resolved_name is a null pointer, the behavior of realpath() is implementation-defined.

RETURN VALUE
       Upon  successful completion, realpath() shall return a pointer to the resolved name. Otherwise, realpath() shall return a
       null pointer and set errno to indicate the error, and the contents of the buffer pointed to by  resolved_name  are  unde-
       fined.

ERRORS
       The realpath() function shall fail if:

       EACCES Read or search permission was denied for a component of file_name.

       EINVAL The file_name argument is a null pointer.

       EIO    An error occurred while reading from the file system.

       ELOOP  A loop exists in symbolic links encountered during resolution of the path argument.

       ENAMETOOLONG
              The length of the file_name argument exceeds {PATH_MAX} or a pathname component is longer than {NAME_MAX}.

       ENOENT A component of file_name does not name an existing file or file_name points to an empty string.

       ENOTDIR
              A component of the path prefix is not a directory.


       The realpath() function may fail if:

       ELOOP  More than {SYMLOOP_MAX} symbolic links were encountered during resolution of the path argument.

       ENAMETOOLONG
              Pathname resolution of a symbolic link produced an intermediate result whose length exceeds {PATH_MAX}.

       ENOMEM Insufficient storage space is available.


       The following sections are informative.

EXAMPLES
   Generating an Absolute Pathname
       The  following  example generates an absolute pathname for the file identified by the symlinkpath argument. The generated
       pathname is stored in the actualpath array.


              #include <stdlib.h>
              ...
              char *symlinkpath = "/tmp/symlink/file";
              char actualpath [PATH_MAX+1];
              char *ptr;


              ptr = realpath(symlinkpath, actualpath);

APPLICATION USAGE
       None.

RATIONALE
       Since the maximum pathname length is arbitrary unless {PATH_MAX} is defined, an application  generally  cannot  supply  a
       resolved_name buffer with size {{PATH_MAX}+1}.

FUTURE DIRECTIONS
       In  the  future,  passing  a  null pointer to realpath() for the resolved_name argument may be defined to have realpath()
       allocate space for the generated pathname.

SEE ALSO
       getcwd(), sysconf(), the Base Definitions volume of IEEE Std 1003.1-2001, <stdlib.h>

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003  Edition,  Standard  for
       Information  Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copy-
       right (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any
       discrepancy  between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard  is  the  referee   document.   The   original   Standard   can   be   obtained   online   at   http://www.open-
       group.org/unix/online.html .



IEEE/The Open Group                                           2003                                                  REALPATH(3P)